The objective of this research work is to gain a better understanding of the molecular mechanism of regulation of protein synthesis initiation in mammalian cells and the roles of different factors involved in this process. Specific research goals are: (1) Studies of regulation of protein synthesis initiation in mammalian cells by eIF-2 kinases (HRI, dsI), Co-eIF-2B, Co-eIF-2C and sRF. (2) Development of radioimmunoassays for peptide chain initiation factors and eIF-2 kinases. (3) Studies of the regulation of protein synthesis by eIF-2 kinases in animal cells under different conditions of growth and development.